Oxybenzoyl polyester coatings

ABSTRACT

A process for reducing the porosity of an oxybenzoyl polyester film by subjecting the surface of the film to a shearing action.

United States Patent Economy et a1.

[is] 3,656,994 [4 1 Apr. 1%, 1972 [54] OXYBENZOYL POLYESTER COATINGS [72] Inventors: James Economy, Buffalo; Steve G. Cottis,

Buffalo; Bernard E. Nowak, Lancaster, all

of NY.

[73] Assignee: The Carborundum Company, Niagara Falls, NY.

[22] Filed: May 28, 1969 211 Appl. No.: 828,693

[52] U.S.Cl ..1l7/62,117/21,117/64, 1l7/65.2, 117/105.2, 117/93.1 PF, 117/132 E,

[51] lnt.Cl. ..B32b 15/08, B44d 1/44, B44d U097 [58] Field ofSearch ..117/132 C, 64, 62, 232,21, 1l7/65.2,11l,128.4,1611(;264/119,126, 323,

[56] References Cited UNITED STATES PATENTS 2,471,023 5/1949 Cook et a1. ..260/78.3

2,760,229 8/1956 Cheney et a1. ..118/405 3,039,994 6/1962 Gleim ..260/47 C 3,197,324 7/1965 Brooks... ..117/21 3,443,007 5/1969 Hardy ..264/323 3,444,131 5/1969 Rosenbrock et a1.. ...1 17/1284 3,502,623 3/1970 Harworth et al.....' ..1l7/l28.4

FOREIGN PATENTS OR APPLICATIONS 660,883 11/1951 Great Britain ..260/47 C Primary E.raminerWilliam D. Martin Assistant Examiner-Wil1iam R. Trenor An0rneyK. W. Brownell [5 7] ABSTRACT A process for reducing the porosity of an oxybenzoyl polyester film by subjecting the surface of the film to a shearing action.

11 Claims, 1 Drawing Figure PATENTEBAPR 18 I972 I 3. 656, 994

IIII'II 4 INVENTORS JAMES ECONOMY STEVE GUST COTTIS BERNARD EDWARD NOWAK ATTORNEY OXYBENZOYL POLYESTER COATINGS According to certain recently discovered techniques it is now possible to produce high molecular weight oxybenzoyl polyesters which are highly resistant to acids and solvents at temperatures up to and sometimes exceeding 700 F. Because of the advantageous physical and chemical properties of these polyesters considerable effort has been expended in attempting to find processes for providing a substrate coated with these polyesters. One process that has met with limited success is the application of the polyester in a hot particulate form onto the substrate by various methods such as flame spraying. While such processesprovide good adhesion of the polyester film to the substrate, they unfortunately produce a film of high porosity due principally to voids and/or pinholes in the film. This porosity adversely affects the electrical properties of the coating, and permits the passage of acids, bases and solvents through the film which can result in undesirable attack of the underlying substrate. An additional disadvantage of the above described process is that it results in a film having a rough surface texture.

It is therefore an object of the present invention to provide a process for producing substrates coated with oxybenzoyl polyesters which is substantially free of one or more of the disadvantages of prior processes.

Another object is to provide an improved process for reducing the porosity of an oxybenzoyl polyester film.

A further object is to provide an improved process for producing a substrate coated with an oxybenzoyl polyester film which is resistant to attack by acids, bases and solvents.

A still further object is to provide an improved process for producing a substrate having an oxybenzoyl polyester film with a smooth surface texture.

Yet another object is to provide an improved substrate having an oxybenzoyl polyester coating thereon.

Additional objects and advantages of the present invention will be apparent to those skilled in the art by reference to the following detailed description thereof and the single figure of the drawing which is a schematic representation of a preferred embodiment of the process of the present invention.

According to the present invention there is provided a process for reducing the porosity of an oxybenzoyl polyester film by subjecting the surface of the film to a shearing action preferably in a direction parallel to the surface of the film.

The shearing action can be effected in a number of different ways. For example it can be accomplished by abrading the surface of the film with a polishing wheel or other rotary instrument containing a fine grit such as sand paper. Alternatively the shearing action can be applied by a smooth surface such as the surface of a smooth rotating roller or simply a hand held laboratory spatula.

The invention may be better understood by reference to the single FIGURE of the drawing wherein there is schematically shown an apparatus 10 suitable for practicing the process of the present invention. In this embodiment a flame spray gun 11 comprising a holder 12 for the oxybenzoyl polyester and a nozzle 13 connected to the holder 12 by a tube 14 is employed to first mix oxygen and acetylene from sources not shown and then pass this mixtiire through the tube 14 drawing the oxybenzoyl polyester from the holder 12 by venturi action and projecting the mixture 15 of hot gases and oxybenzoyl polyester onto the substrate 16 to form a film 17. The surface 18 of the film 17 is rough and the body thereof contains pinholes and voids due to incomplete coalescence of the particles of oxybenzoyl polyester present in the mixture 15. The substrate 16 is moved in the direction of the arrow 19 and passes under a roller 20 moving in the direction of the arrow 21. The surface of the roller 20 can be highly polished or can'be an abrasive wheel of silicon carbide or any other hard material which will abrade the surface. As the substrate 16 passes under the roller 20 the surface 18 of the film 17 is subjected to a shearing action by the roller 20 in a direction substantially parallel to the surface 18 of the film 17. The shearing action is preferably applied with sufficient force to cause some plastic deformation of the film 17 to produce a substrate 16 coated with a film 17 the upper surface 22 of which is impervious.

The oxybenzoyl polyesters useful in the present invention are generally those of repeating units of Formula 1:

wherein R is a member selected from the group consisting of benzoyl, lower alkanoyl, or preferably hydrogen; wherein R is hydrogen, benzyl, lower alkyl, or preferably phenyl and p is an integer from 3 to 600 and preferably 30 to 200. These values of p correspond to a molecular weight of about 1,000 to 72,000 and preferably 3,500 to 25,000. The synthesis of these polyesters is described in detail in U.S. Pat. application Ser. No. 619,577 filed Mar. 1, 1967 and now abandoned, entitled Polyesters Based on Hydroxybenzoic Acids," the disclosure of which is incorporated herein by reference.

Another preferred class of oxybenzoyl polyesters are copolyesters of recurring units of Formulae l, 111 and 1V:

wherein X is 0 or SO m is 0 or 1; n is 0 or 1; q:r 10:15 to 15:10; p:q 1:100 to :1; p-l-q-l-r= 3 to 600 and preferably 30 to 200 these values corresponding to molecular weights of from 500 to over 72,000 and preferably from 3,500 to 25,000. The carbonyl groups of the moiety of Formula 1 or 111 are linked to the oxy groups of a moiety of Formula 1 or IV; the oxy groups of the moiety of Formula 1 or IV are linked to the carbonyl groups of the moiety of Formula 1 or 111.

The preferred copolyesters are those of recurring units of Formula V:

l Q Q Q.

The synthesis of these polyesters is described in detail in U.S. Pat. application Ser. No. 828,484 filed concurrently herewith entitled P-Oxybenzoyl Copolyesters the disclosure of which is incorporated herein by reference.

The polyesters useful in thepresent invention can also be chemically modified by various means such as by inclusion in the polyester of monofunctional reactants such as benzoic acid, or trior higher functional reactants such as trimesic acid or cyanuric chloride. The benzene rings in these polyesters are preferably unsubstituted but can be substituted with non-interfering substituents examples of which include among others halogen such as chlorine or fluorine, lower alkoxy such as methoxy and lower alkyl such as methyl.

A wide variety of substrates can be employed in the present invention examples of which include among others ferrous metals such as iron or steel, non-ferrous metals such as brass, titanium, aluminum or copper, and non-metals such as stone or concrete.

The polyesters useful in the present invention can be employed in their pure form, mixed, with one another or with a wide variety of organic and/or inorganic fillers. Examples of suitable organic fillers include among others polyhalogenated addition polymers such as polytetrafluoroethylene and condensation polymers such as polyimides. Examples of suitable inorganic fillers include among others graphite, zinc, molybdenum disulfide, and glass fibers. These fillers can comprise up to 70 wt percent of the combined weight of polyester and filler.

The invention is further illustrated by the following examples in which all parts and percentages are by weight unless otherwise indicated. These non-limiting examples are illustrative of certain embodiments designed to teach those skilled in the art how to practice the invention and to represent the best mode contemplated for carrying out the invention.

EXAMPLE 1 A mixture of 856 g of phenyl para-hydroxybenzoate, 0.015 g of tetra-n-butyl orthotitanate and 1,800 g of a polychlorinated polyphenyl solvent (b.p. 3 60370 C) is heated, with constant stirring and under an atmosphere of flowing nitrogen, at l70-l90 C for 4 hours and then at 340-360 C for hours. Early in this heating cycle the mixture becomes a homogenous liquid. During the heating cycle condensation occurs, accompanied by the distillation of phenol, and the polyester which is produced thereby forms a precipitate. The mixture is cooled to room temperature and extracted with acetone to remove the polychlorinated polyphenyl solvent, and the product is dried overnight in vacuum at 60 C. A yield of 377 g of polyester powder is obtained, consisting essentially of a para-oxybenzoyl polyester.

EXAMPLE 2 This example illustrates the synthesis of a copolyester useful in the present invention.

The following quantities of the following ingredients are combined as indicated.

ltem Ingredient Quantity Grams Moles A P-hydroxybenzoic Acid 138 l B Phenyl acetate 170 1.25 C Therminol 77 500 D Diphenyl Terephthalate 3 l 8 l E Hydrogen Chloride F Hydroquinone 111 1.01 G Thcrminol 77 500 Items A D are charged to a four-necked, round bottom flask fitted with a thermometer, a stirrer, a combined nitrogen and HCl inlet and an outlet connected to a condenser. Nitrogen is passed slowly through the inlet. The flask and its contents are heated to 180 C whereupon HCl is bubbled through the reaction mixture. The outlet head temperature is kept at l 10-l20 C by external heating during the p-hydroxybenzoic acid, phenyl acetate ester exchange reaction.

The flask and its contents are stirred at 180 C for 6 hours whereupon the HCl is shut off, the outlet head temperature raised to 180-190 C and the mixture stirred at 220 C for 3.5 hours. Up to this point, 159 grams of distillate are collected in the condenser. ltem F is then added and the temperature gradually increased from 220 C to 320 C over a period of 10 hours (10 C/hr.). Stirring is continued at 320 C for 16 hours and then for 3 additional hours at 340 C to form a slurry. The total amount of distillate, consisting of phenol, acetic acid and phenyl acetate, amounts to 384g. ltem G is added and the reaction mixture permitted to cool to 70 C. Acetone (750 ml) is added and the slurry filtered, the solids are extracted in a Soxhlet with acetone to remove items C and G. The solids are dried in vacuo at 110 C overnight whereupon the resultant copolyester (320g, 89.2 percent of theory) is recovered as a granular powder.

EXAMPLE 3 This example illustrates the process of the present invention wherein the polyester film is subjected to a shearing action compared to a control film.

A V4 in. thick mild steel plate substrate is flame sprayed with the granular polyester of Example 1 depositing the polyester as a 0.003 in. thick film. The film is permitted to cool to room temperature and the coated plate cut into two identical parts. The first part is immersed untreated in concentrated hydrochloric acid. Bubbles form on the surface of the polyester film and in a few minutes the entire film lifts away from the substrate.

The second part is lightly polished with a rotary abrasive polishing disk having No. 000 sandpaper thereon and then immersed in hydrochloric acid of the same strength. No bubbles appear on the surface of the polyester film which continues to adhere tenaciously to the substrate.

EXAMPLE 4 The procedure of Example 3 is repeated except that the shearing action is applied to the film by a hand held laboratory spatula instead of a polishing disk with similar results.

EXAMPLE 5 The procedure of Example 3 is repeated except that the film and substrate are heated to C. before polishing with similar results.

EXAMPLE 6 This example illustrates the process of the present invention wherein the film was deposited by the hot dip procedure.

A steel plate A in. X l in. X 5 in. was heated to 600 C and dipped into a container of the polyester of Example I. The plate is then withdrawn and the adhering polyester film permitted to cool and polished as in Example 2.

EXAMPLE 7 The procedures of Examples 3 through 6 are repeated except that the polyester of Example 1 is replaced by the polyester of Example 2 with similar results.

EXAMPLE 8 The procedure of Example 3 is repeated except that the spraying there done by a flame spray apparatus is now done by a plasma spray apparatus. The polyester adheres even better to the substrate.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described above and as defined in the appended claims.

What is claimed is:

1. A process of producing a substrate coated with an impervious film of an oxybenzoyl polyester comprising forming a porous film of said oxybenzoyl polyester on said substrate and applying a shearing action to the surface of said porous film in a direction substantially parallel to the surface of the film and with sufficient force to cause plastic deformation of the film whereby the surface of the film is rendered impervious, said oxybenzoyl polyester having a molecular weight of at least about 3,500 and being selected from the group consisting of a. A polyester having the formula group consisting of benzoyl,

lS phenyl; and p is an integer (III) L A l.

wherein X is or -SO m is 0 or 1; n is 0 or l;q:r= :15 to l5:l0;p:q= 1:100 to l00:l;p+q+r=30to 200; the carbonyl groups of the moiety of Formula I or III are linked to the oxy groups of the moiety of Formula I or IV; and the oxy groups of the moiety of Formula I or IV are linked to the carbonyl groups of the moiety of Formula 1 or ill.

2. A process as set forth in claim 1 wherein said substrate is metal.

3. A process as set forth in claim 2 wherein said porous film is formed by flame spraying said oxybenzoyl polyester on said substrate.

4. A process as set forth in claim 2 wherein said porous film is formed by plasma spraying said oxybenzoyl polyester on said substrate.

5. A process as set forth in claim 1 wherein said oxybenzoyl polyester has the formula l Q l wherein R is selected from the group consisting of benzoyl, lower alkanoyl and hydrogen; R is phenyl; and p is an integer from 30 to 200.

6. A process as set forth in claim 5 wherein R is selected from the group consisting of lower alkanoyl and hydrogen.

7. A process as set forth in claim 5 wherein R is hydrogen.

8. A process as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3,500 to 25,000 and consists essentially of recurring structural units of Formulas I, Ill and IV.

ybenzoyl polyester consists essentially of recurring units of the formula 

2. A process as set forth in claim 1 wherein said substrate is metal.
 3. A process as set forth in claim 2 wherein said porous film is formed by flame spraying said oxybenzoyl polyester on said substrate.
 4. A process as set forth in claim 2 wherein said porous film is formed by plasma spraying said oxybenzoyl polyester on said substrate.
 5. A process as set forth in claim 1 wherein said oxybenzoyl polyester has the formula
 6. A process as set forth in claim 5 wherein R1 is selected from the group consisting of lower alkanoyl and hydrogen.
 7. A process as set forth in claim 5 wherein R1 is hydrogen.
 8. A process as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3,500 to 25,000 and consists essentially of recurring structural units of Formulas I, III and IV.
 9. A process as set forth in claim 8 wherein m is
 0. 10. A process as set forth in claim 8 wherein n is
 0. 11. A process as set forth in claim 8 wherein said oxybenzoyl polyester consists essentially of recurring units of the formula 